钠离子电池无粘结剂二氧化钛负极材料的合成

As an important part of rechargeable sodium-ion batteries, electrode materials have a direct impact on the energy density of batteries. Binders tend to be added to stabilize the structure of the electrode during the fabrication of the electrode materials, but the addition of binders will reduce the specific capacity and affect the rate of ion migration of electrode materials. Here,binder-free titanium dioxide/titanium(TiO₂/Ti)nanowire array electrodes are prepared by in-situ growth on titanium foil/mesh by hydrothermal process. The effects of different titanium substrates and hydrothermal reaction temperatures on the physical and electrochemical properties of TiO₂/Ti nanowire array electrodes are investigated systematically. The results show that different titanium substrates and hydrothermal reaction temperatures heavily affect the micromorphology and electrochemical properties of the grown TiO₂ nanowires. Among them, the TiO₂ nanowires grown on titanium mesh (0.15 mm) by hydrothermal reaction at 220 ℃ (TiW-100-220) are cobweb-like with a large specific surface area. Moreover, the TiO₂ nanowires grown on Ti mesh(0.15 mm) at 220 ℃ are anatase, which have a lower activation energy than TiO₂ nanowires with other crystal structures. The main sodium storage process of TiW-100-220 is controlled by pseudocapacitance reaction, which has better electrochemical performance. The discharge capacity and coulombic efficiency of TiW-100-220 anode is 986 mAh g^-1 and 21.7% in the first cycle. The discharge capacity of TiW-100-220 anode gradually stabilizes at 240 mAh g^-1 from the second cycle. The discharge capacity of TiW-100-220 anode is 228 mAh g^-1 after 200 cycles, and the coulombic efficiency is stable at about 99.3%. Even at a high current density of 3200 mA g^-1, the discharge capacity of TiW-100-220 anode can still reach 152 mAh g^-1. The binder-free electrode materials greatly increase the specific capacity of the electrode materials, which might be possible to offer theoretical significance and reference value to design a high energy density battery in the future.